Contents

History

The forerunner of the DSN was established in January, 1958, when
JPL, then under contract to the U.S. Army, deployed portable radio
tracking stations in Nigeria, Singapore, and California to receive
telemetry and plot the orbit of the Army-launched Explorer 1, the first
successful U.S. satellite.[1] NASA
was officially established on October 1, 1958, to consolidate the
separately developing space-exploration programs of the Army, Navy,
and Air Force into one civilian organization[2].

On 3 December 1958, the JPL was transferred from the Army to
NASA and given responsibility for the design and execution of lunar
and planetary exploration programs using remotely-controlled
spacecraft. Shortly after the transfer of the JPL to NASA, NASA
established the concept of the Deep Space Network as a separately
managed and operated communications system that would accommodate
all deep space missions, thereby avoiding the need for each flight
project to acquire and operate its own specialized space
communications network. The DSN was given responsibility for its
own research, development, and operation in support of all of its
users. Under this concept, it has become a world leader in the
development of low-noise receivers; large parabolic-dish antennas;
tracking, telemetry, and command systems; digital signal
processing; and deep space navigation.

The largest antennas of the DSN are often called on during
spacecraft emergencies. Almost all spacecraft are designed so
normal operation can be conducted on the smaller (and more
economical) antennas of the DSN, but during an emergency the use of
the largest antennas is crucial. This is because a troubled
spacecraft may be forced to use less than its normal transmitter
power, attitude control problems
may preclude the use of high-gain antennas, and recovering
every bit of telemetry
is critical to assessing the health of the spacecraft and planning
the recovery. The most famous example is the Apollo 13 mission, where limited battery
power and inability to use the spacecraft's high gain antennas
reduced signal levels below the capability of the Manned Space Flight
Network, and the use of the biggest DSN antennas (and the
Australian Parkes Observatory radio telescope)
was critical to saving the lives of the astronauts. Although in
this case Apollo was also a USA/NASA mission, DSN also provides
this same emergency service to other space agencies as well, in a
spirit of inter-agency and international cooperation. For example,
the recovery of the Solar and Heliospheric
Observatory (SOHO) mission of the European Space Agency (ESA) would
not have been possible without the use of the largest DSN
facilities.

General
information

Deep Space Network Operations Center

DSN currently consists of three deep-space communications
facilities placed approximately 120 degrees apart around the
world[3]. They
are:

Each facility is situated in semi-mountainous, bowl-shaped
terrain to shield against radio frequency interference. This
strategic placement permits constant observation of spacecraft as
the Earth rotates, and helps to make the DSN the largest and most
sensitive scientific telecommunications system in the world.

NASA's scientific investigation
of the Solar System is being accomplished mainly through the use of
unmanned spacecraft. The DSN provides the
vital two-way communications link that guides and controls these
machines, and brings back the images and new scientific information
they collect. All DSN antennas are steerable, high-gain, parabolic reflector
antennas.

The network is a facility of the JPL and is managed and operated
for NASA by the California Institute of
Technology (Caltech). The Interplanetary Network Directorate
(IND) manages the program within JPL and is charged with the
development and operation of it. The IND is considered to be JPL's
focal point for all matters relating to telecommunications,
interplanetary navigation, information systems, information
technology, computing, software engineering, and other relevant
technologies.

While the IND is best known for its duties relating to the Deep
Space Network, the organization also maintains the JPL Advanced
Multi-Mission Operations System (AMMOS) and JPL's Institutional
Computing and Information Services (ICIS).[4][5]

Antennas

Each complex consists of at least four deep space terminals
equipped with ultra-sensitive receiving systems and large
parabolic-dish antennas. There are:

One 34-metre (110 ft) diameter High Efficiency
antenna.

One or more 34-metre (110 ft) Beam Waveguide antennas
(three at the Goldstone
Complex, two at the Robledo de Chavela complex (near
Madrid), and one at the
Canberra Complex).

One 26-metre (85 ft) antenna.

One 70-metre (230 ft) antenna.

Five of the 34-metre (110 ft) beam waveguide antennas were
added to the system in the late 1990s. Three were located at
Goldstone, and one each at Canberra and Madrid. A second 34-metre
(110 ft) beam waveguide antenna (the network's sixth) was
completed at the Madrid complex in 2004.

The ability to array several antennas was incorporated to
improve the data returned from the Voyager 2 Neptune encounter, and
extensively used for the Galileo
spacecraft, when the high gain antenna did not deploy
correctly[6]. The
array electronically links the 70-metre (230 ft) dish antenna
at the Deep Space Network complex in Goldstone, California, with an
identical antenna located in Australia, in addition to two 34-metre
(110 ft) antennas at the Canberra complex. The California and
Australia sites were used concurrently to pick up communications
with Galileo.

Arraying of antennas within the three DSN locations is also
used. For example, a 70-metre (230 ft) dish antenna can be
arrayed with a 34-meter dish. For especially-vital missions, like
Voyager 2, the Canberra 70-metre (230 ft) dish can be arrayed
with the Parkes Radio Telescope in Australia; and the Goldstone
70-meter dish can be arrayed with the Very Large Array of antennas in New
Mexico. Also, two or more 34-metre (110 ft) dishes at one DSN
location are commonly arrayed together.

All the stations are remotely operated from a centralized Signal
Processing Center at each complex. These Centers house the
electronic subsystems that point and control the antennas, receive
and process the telemetry data, transmit commands, and generate the
spacecraft navigation data.

Once the data is processed at the complexes, it is transmitted
to JPL for further processing and for distribution to science teams
over a modern communications network, frequently using satellite
communications.

DSN
and the Apollo program

Although normally tasked with tracking unmanned spacecraft, the
Deep Space Network (DSN) also contributed to the communication and
tracking of Apollo
missions to the Moon, although
primary responsibility was held by the Manned Space Flight
Network. The DSN designed the MSFN stations for lunar
communication and provided a second antenna at each MSFN site (the
MSFN sites were near the DSN sites for just this reason). Two
antennas at each site were needed both for redundancy and because
the beam widths of the large antennas needed were too small to
encompass both the lunar orbiter and the lander at the same time.
DSN also supplied some larger antennas as needed, in particular for
television broadcasts from the Moon, and emergency communications
such as Apollo 13.[7]

From a NASA report describing how the DSN and MSFN cooperated
for Apollo:[8]

Another critical step in the evolution of the Apollo Network
came in 1965 with the advent of the DSN Wing concept. Originally,
the participation of DSN 26-m antennas during an Apollo Mission was
to be limited to a backup role. This was one reason why the MSFN
26-m sites were collocated with the DSN sites at Goldstone, Madrid,
and Canberra. However, the presence of two, well-separated
spacecraft during lunar operations stimulated the rethinking of the
tracking and communication problem. One thought was to add a dual
S-band RF system to each of the three 26-m MSGN antennas, leaving
the nearby DSN 26-m antennas still in a backup role. Calculations
showed, though, that a 26-m antenna pattern centered on the landed
Lunar Module would suffer a 9-to-12 db loss at the lunar horizon,
making tracking and data acquisition of the orbiting Command
Service Module difficult, perhaps impossible. It made sense to use
both the MSFN and DSN antennas simultaneously during the
all-important lunar operations. JPL was naturally reluctant to
compromise the objectives of its many unmanned spacecraft by
turning three of its DSN stations over to the MSFN for long
periods. How could the goals of both Apollo and deep space
exploration be achieved without building a third 26-m antenna at
each of the three sites or undercutting planetary science
missions?

The solution came in early 1965 at a meeting at NASA
Headquarters, when Eberhardt Rechtin suggested what is now known as
the "wing concept". The wing approach involves constructing a new
section or "wing" to the main building at each of the three
involved DSN sites. The wing would include a MSFN control room and
the necessary interface equipment to accomplish the following: i.
Permit tracking and two-way data transfer with either spacecraft
during lunar operations. 2. Permit tracking and two-way data
transfer with the combined spacecraft during the flight to the Moon
3. Provide backup for the collocated MSFN site passive track
(spacecraft to ground RF links) of the Apollo spacecraft during
trans-lunar and trans-earth phases. With this arrangement, the DSN
station could be quickly switched from a deep-space mission to
Apollo and back again. GSFC personnel would operate the MSFN
equipment completely independently of DSN personnel. Deep space
missions would not be compromised nearly as much as if the entire
station's equipment and personnel were turned over to Apollo for
several weeks.

The need to support "legacy" missions that have remained
operational beyond their original lifetimes but are still returning
scientific data. Programs such as Voyager have been operating long past
their original mission termination date. They also need some of the
largest antennas.

The DSN's deferred maintenance of its 70m antennas. This causes
problems where they are out of service for months at a time.
Furthermore, they are reaching the end of their lives. At some
point they will need to be replaced. The leading candidate is an
array of smaller dishes[9][10].

By 2020, the DSN will be required to support twice the number
of missions it was supporting in 2005.

See also

Ulysses' extended mission operation terminated June 30, 2009.
The extension permitted a third flyby over the Sun's poles in
2007–2008.

The two Voyager spacecraft continue to operate, with some loss
in subsystem redundancy, but retain the capability of returning
science data from a full complement of VIM science instruments.
Both spacecraft also have adequate electrical power and attitude
control propellant to continue operating until around 2020, when
the available electrical power will no longer support science
instrument operation. At this time, science data return and
spacecraft operations will cease.